Magnetic latch for a door



Oct. 31, 1967 M. HEKELAAR MAGNETIC LATCH FOR A DOOR Filed March 22, 1965 INVENTOR MAARTEN HEKELAAR United States Patent 3,350,127 MAGNETIC LATCH FOR A DOOR Maarten Hekelaar, Emmasingel, Eindhoven, Netherlands, assignor to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed Mar. 22, 1965, Ser. No. 441,456 Claims priority, application Netherlands, Mar. 24, 1964, 643,113 6 Claims. (Cl. 292-2515) The invention relates to a magnetic latch for a door and the like, comprising a lock bolt adapted to co-operate magnetically with a locking plate and being slidable and tiltable in a guide, the lock bolt and the locking plate being separated by tilting movement.

Magnetic locks generally of the kind set forth above are known from US. Patent 2,808,281.

The invention is characterized in that the bolt is adapted to tilt to a restricted extent in the direction of movement of the door as it is opened. The locking plate is provided with a wedge-shaped ramp, so that when the door is pushed for opening the lock bolt is tilted by the ramp and, after the bolt has reached a given slanting position, it slides along said ramp upon further movement of the door, so that it is pushed back into the bolt guide.

The invention provides a possibility of opening the door by exerting a slight force in the direction of movement for opening by pushing or pulling a handle in the direction of opening.

In an advantageous embodiment of the invention the bolt is provided laterally with a lug, in the direction of movement, said lug co-operating with a stationary portion of the guide.

A-fter the bolt has tilted slightly, the end of the lug comes into contact with the stationary portion of the guide. The bolt then tilts further about said end and disappears in the guide, whilst it simultaneously passes by the ramp.

By the use of the lug the outward movement of the lock bolt is restricted, whilst the effect of the end, as a pivot for guiding the tilting movement, is determined.

According to a further aspect of the invention the lug is formed by an arm with an adjustable screw, the head of which is spherical, said head being located in a hole passing through the sheating of the housing.

The screw can be readily screwed out of the sheating, i.e. the front side of a door lock, by means of a screw driver, the outward movement of the lock bolt being thus adjusted and the manner of tilting being determined by the pivot.

An advantageous embodiment comprises a lock bolt provided with an arrester for the tilting movement, which arrester is coupled with a shaft extending in the direction of movement and provided with at least one door knob, whilst by pulling or pushing the door knob the arrester is first put out of operation and then the lock is opened.

An objection to large doors using conventional latches is that they open when subjected to minor forces, for example wind. This troublesome eifect is avoided by using the arrester according to the invention.

The invention will be described in greater detail with reference to the drawing in which:

FIG. 1 is a longitudinal sectional view of a magnetic latch according to the invention.

FIG. 2 shows a variation thereof of a to the invention and FIG. 3 shows a detail along the line III-I'II FIG. 2.

FIG. 1 shows a magnetic, so-called push-pull latch comprising a magnetic bolt 1, which co-operates with a locking plate 2.

The bolt 1 is slidable and tiltable in the guide 6 of a latch according door 40 and the locking plate 2 is mounted in a conventional manner, for example with the aid of screws (not shown) in the door jamb '3.

The bolt 1 consists of a magnet 4 of MAGNADUR, which is provided on two opposite sides with pole pieces 5 and 7. The pole piece 7 is provided with an arm or lug 8, in which :a screw 9 is threaded. The screw head 10 is accessible through a hole 11 in the sheating so that the bolt can be adjusted.

The latch is provided with an arrester comprising a pawl 12. In the closed position the lug 13 bears on the side of the bolt 1 to prevent it from tilting. A shaft 14, is provided with door knobs 15 and 16. The shaft 14 is adapted to move axially through brackets 17 and 18. The shaft 14 is surrounded by a helical spring 19, which is enclosed between the collar 20 and the tag 22, which also forms a collar. One end of the helical spring 19 cooperates through the tag 22 with the rotatable pawl 12.

The shaft 14 is furthermore provided with a bevelled arrester lug 23. The locking plate 2 is provided with a wedge-shaped ramp 24 and recess 25. In the closed state of the lock the front side of the lock bolt is located in said recess 25.

The lock operates as follows. By pulling the door knob 16, or by pushing the door knob 15, the shaft 14 moves in an axial direction so that the pawl 12 is free to pivot about .pin 12a in a counterclockwise direction, since the arrester lug 23 is moved out of the path of the pawl 12.

The door (as it is pulled or pushed via a door handle) exerts on the bolt 1 a lateral force so that the bolt tilts about the edge forced against the wedge-shaped ramp 24. After the bolt 1 has reached a given slanting position, the head of screw 10 serves as a fulcrum, whereby, as the door is pushed further the bolt slides into the guide 6.

When the doorknob 15 or 16 is released, the spring 19 returns the shaft to its initial position as shown in FIG. 1. The force of the spring 19 which causes the shaft 14 to return to its initial position also acts on the tag 22 which engages the pawl 12 thereby causing the pawl 12 to rotate the bolt 1 into its initial position. The arrester lug 23 also returns to its original position and will thereby block further rotation of the pawl 12.

FIGS. 2 and 3 show a similar magnetic lock with a different arrester. The arrester comprises in this case a shaft 14 and a helical spring 19. The shaft 14 is provided with a toothed rack 30, which co-operates with a pinion 31, which is coupled with a cut or semi-circular wheel 32, fulfilling the function of the pawl 12 of the magnetic lock of FIG. 1. When the lock is opened, the shaft 14 moves in an axial direction as before, so that through the pinion 31 the wheel 32 turns to the right, leaving the bolt free to tilt. When the knob is' released, the wehel 32 returns the bolt to its non-tilted position.

What is claimed is:

1. A magnetic latch for a door comprising the combination of a locking plate of ferromagnetic material having a ramp portion and a recess for receiving a bolt, and a latch means; said latch means including a permanent magnet bolt, a bolt guide, said bolt being tiltable in the direction of opening movement of said door and slideable within saidguide, means operatively associated with said bolt for preventing tilting of said bolt and inadvertent opening of said door, knob means for moving said tilting prevention means to an inoperative position, and means for slidably positioning said bolt within said guide.

2. A magnetic latch according to claim 1 wherein said last-named means comprises an adjustable member attached to said bolt forming a fulcrum for tilting movement thereof and slidably positioning said bolt in said guide upon opening movement of said door when said bolt resides in said recess of said locking plate.

'3. A magnetic latch according to claim 2 wherein said adjustable member comprises an arm extending outwardly from said bolt in said direction of tilting, a threaded bore in said arm and a screw member in said bore, an opening in said latch means for access to said screw for adjustment thereof and a head on said screw member in pivotal engagement with the edge defining said opening.

4. A magnetic latch according to claim 1 wherein said tilting prevention means comprises a pivotal pawl member operatively coupled with said bolt, and a lug attached to an axially moving door knob shaft of said door knob means for positioning said lug for blocking movement of said pawl when said shaft is in its normal inactive position; the door opening force applied to said shaft moving said lug from said blocking position.

5. A magnetic latch according to claim 1 wherein said tilting prevention means comprises a semi-circular member operatively coupled with said bolt, a pinion connected with said semi-circular member, said door knob means including an axially movable door knob shaft, said shaft having a rack member coupled with said pinion whereby said semi-circular wheel is rotated for disengagement with said bolt upon movement of said shaft to its door opening position.

6. A magnetic latch according to claim 1 wherein said bolt comprises a flat permanent magnet having a plateshaped pole piece on opposite sides of said permanent magnet, one said pole piece engaging said locking plate for tilting said bolt, and said one pole piece being included in said means for sliding said bolt within said guide.

References Cited UNITED STATES PATENTS 605,170 6/ 1898 Meigs. 1,087,193 2/ 1914 Skinner. 2,808,281 10/1957 Poe 292-251.15 3,129,968 4/1964 Graham 292251.5 X 3,188,840 6/ 1965 Wartian 292-254 X FOREIGN PATENTS 1,302,936 7/1962 France.

216,547 11/1909 Germany.

RICHARD E. MOORE, Primary Examiner. 

1. A MAGNETIC LATCH FOR A DOOR COMPRISING THE COMBINATION OF A LOCKING PLATE OF FERROMAGNETIC MATERIAL HAVING RAMP PORTION AND A RECESS FOR RECEIVING A BOLT, AND A LATCH MEANS; SAID LATCH MEANS INCLUDING A PERMANENT MAGNET BOLT, A BOLT GUIDE, SAID BOLT BEING TILTABLE IN THE DIRECTION OF OPENING MOVEMENT OF SAID DOOR AND SLIDEABLE WITHIN SAID GUIDE, MEANS OPERATIVELY ASSOCIATED WITH SAID BOLT FOR PREVENTING TILTING OF SAID BOLT AND INADVERTENT OPENING OF SAID DOOR, KNOB MEANS FOR MOVING SAID TILTING PREVENTION MEANS TO AN INOPERATIVE POSITION, AND MEANS FOR SLIDABLY POSITIONING SAID BOLT WITHIN SAID GUIDE. 